<i>Plasmodium cynomolgi</i> Co-infections among Symptomatic Malaria Patients, Thailand
Chaturong Putaporntip, Napaporn Kuamsab, Urassaya Pattanawong, Surasuk Yanmanee, Sunee Seethamchai, Somchai Jongwutiwes
Abstract
P lasmodium cynomolgi, a simian malaria parasite, pos- sesses biological and genetic characteristics akin to those of the most widespread human malaria parasite, P. vivax. Although P. cynomolgi circulates among monkey species such as long-tailed macaques (Macaca fascicularis) and pig-tailed macaques (M. nemestrina), experimental and accidental transmissions have been implicated in symptomatic infections in humans (1). Several mosquito vectors for human malaria can also transmit P. cynomolgi, posing the risk of cross-species transmission in areas where its natural hosts coexist with people (1,2). Among pig-tailed and long-tailed macaques living in various countries in Southeast Asia, including Thailand, P. cynomolgi infections are not uncommon A case of naturally transmitted P. cynomolgi malaria in a human was reported from eastern Malaysia (5). Subsequent surveillance in western Cambodia and northern Sabah state in Malaysia revealed asymptomatic human infection, albeit at low prevalence (6,7). Symptomatic P. cynomolgi infection was diagnosed in a traveler returning to Denmark from Southeast Asia (8). During testing of symptomatic malaria patients in Thailand, we identified 9 co-infected with cryptic P. cynomolgi and other Plasmodium species.